Move utility method for embedding links in texts from about_chrome_view to a generic class, for future use in other classes.

BUG= none
TEST= chrome "about" dialog still works the same, in ltr and rtl languages.

Review URL: http://codereview.chromium.org/1508018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@43634 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 244 insertions, 0 deletions

diff --git a/views/view_text_utils.cc b/views/view_text_utils.cc
new file mode 100644
index 0000000..2995f26
--- /dev/null
+++ b/views/view_text_utils.cc
@@ -0,0 +1,167 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "views/view_text_utils.h"
+
+#include "app/bidi_line_iterator.h"
+#include "base/i18n/rtl.h"
+#include "base/i18n/word_iterator.h"
+#include "base/logging.h"
+#include "gfx/canvas.h"
+#include "gfx/color_utils.h"
+#include "gfx/size.h"
+#include "views/controls/label.h"
+#include "views/controls/link.h"
+
+namespace view_text_utils {
+
+void DrawTextAndPositionUrl(gfx::Canvas* canvas,
+                            views::Label* label,
+                            const std::wstring& text,
+                            views::Link* link,
+                            gfx::Rect* rect,
+                            gfx::Size* position,
+                            bool text_direction_is_rtl,
+                            const gfx::Rect& bounds,
+                            const gfx::Font& font) {
+  DCHECK(canvas && position);
+
+  // The |text| parameter is potentially a mix of LTR and RTL "runs," where
+  // a run is a sequence of words that share the same directionality. We
+  // initialize a bidirectional ICU line iterator and split the text into
+  // runs that are either strictly LTR or strictly RTL, with no mix.
+  BiDiLineIterator bidi_line;
+  if (!bidi_line.Open(text.c_str(), true, false))
+    return;
+
+  // Iterate over each run and draw it.
+  int run_start = 0;
+  int run_end = 0;
+  const int runs = bidi_line.CountRuns();
+  for (int run = 0; run < runs; ++run) {
+    UBiDiLevel level = 0;
+    bidi_line.GetLogicalRun(run_start, &run_end, &level);
+    DCHECK(run_end > run_start);
+    std::wstring fragment = text.substr(run_start, run_end - run_start);
+
+    // A flag that tells us whether we found LTR text inside RTL text.
+    bool ltr_inside_rtl_text =
+        ((level & 1) == UBIDI_LTR) && text_direction_is_rtl;
+
+    // Draw text chunk contained in |fragment|. |position| is relative to the
+    // top left corner of the label we draw inside, even when drawing RTL.
+    DrawTextStartingFrom(canvas, label, fragment, position, bounds, font,
+        text_direction_is_rtl, ltr_inside_rtl_text);
+
+    run_start = run_end;  // Advance over what we just drew.
+  }
+
+  // If the caller is interested in placing a link after this text blurb, we
+  // figure out here where to place it.
+  if (link && rect) {
+    gfx::Size sz = link->GetPreferredSize();
+    gfx::Insets insets = link->GetInsets();
+    WrapIfWordDoesntFit(sz.width(), font.height(), position, bounds);
+    int x = position->width();
+    int y = position->height();
+
+    // Links have a border to allow them to be focused.
+    y -= insets.top();
+
+    *rect = gfx::Rect(x, y, sz.width(), sz.height());
+
+    // Go from relative pixel coordinates (within the label we are drawing
+    // on) to absolute pixel coordinates (relative to the top left corner of
+    // the dialog content).
+    rect->Offset(bounds.x(), bounds.y());
+    // And leave some space to draw the link in.
+    position->Enlarge(sz.width(), 0);
+  }
+}
+
+void DrawTextStartingFrom(gfx::Canvas* canvas,
+                          views::Label* label,
+                          const std::wstring& text,
+                          gfx::Size* position,
+                          const gfx::Rect& bounds,
+                          const gfx::Font& font,
+                          bool text_direction_is_rtl,
+                          bool ltr_within_rtl) {
+#if defined(OS_WIN)
+  const SkColor text_color = color_utils::GetSysSkColor(COLOR_WINDOWTEXT);
+#else
+  // TODO(beng): source from theme provider.
+  const SkColor text_color = SK_ColorBLACK;
+#endif
+
+  // Iterate through line breaking opportunities (which in English would be
+  // spaces and such). This tells us where to wrap.
+  WordIterator iter(text, WordIterator::BREAK_LINE);
+  if (!iter.Init())
+    return;
+
+  int flags = (text_direction_is_rtl ? gfx::Canvas::TEXT_ALIGN_RIGHT :
+                                       gfx::Canvas::TEXT_ALIGN_LEFT);
+  flags |= gfx::Canvas::MULTI_LINE | gfx::Canvas::HIDE_PREFIX;
+
+  // Iterate over each word in the text, or put in a more locale-neutral way:
+  // iterate to the next line breaking opportunity.
+  while (iter.Advance()) {
+    // Get the word and figure out the dimensions.
+    std::wstring word;
+    if (!ltr_within_rtl)
+      word = iter.GetWord();  // Get the next word.
+    else
+      word = text;  // Draw the whole text at once.
+
+    int w = font.GetStringWidth(word), h = font.height();
+    canvas->SizeStringInt(word, font, &w, &h, flags);
+
+    // If we exceed the boundaries, we need to wrap.
+    WrapIfWordDoesntFit(w, font.height(), position, bounds);
+
+    int x = label->MirroredXCoordinateInsideView(position->width()) +
+                                                 bounds.x();
+    if (text_direction_is_rtl) {
+      x -= w;
+      // When drawing LTR strings inside RTL text we need to make sure we
+      // draw the trailing space (if one exists after the LTR text) to the
+      // left of the LTR string.
+      if (ltr_within_rtl && word[word.size() - 1] == L' ') {
+        int space_w = font.GetStringWidth(L" "), space_h = font.height();
+        canvas->SizeStringInt(L" ", font, &space_w, &space_h, flags);
+        x += space_w;
+      }
+    }
+    int y = position->height() + bounds.y();
+
+    // Draw the text on the screen (mirrored, if RTL run).
+    canvas->DrawStringInt(word, font, text_color, x, y, w, font.height(),
+                          flags);
+
+    if (word.size() > 0 && word[word.size() - 1] == L'\x0a') {
+      // When we come across '\n', we move to the beginning of the next line.
+      position->set_width(0);
+      position->Enlarge(0, font.height());
+    } else {
+      // Otherwise, we advance position to the next word.
+      position->Enlarge(w, 0);
+    }
+
+    if (ltr_within_rtl)
+      break;  // LTR within RTL is drawn as one unit, so we are done.
+  }
+}
+
+void WrapIfWordDoesntFit(int word_width,
+                         int font_height,
+                         gfx::Size* position,
+                         const gfx::Rect& bounds) {
+  if (position->width() + word_width > bounds.right()) {
+    position->set_width(0);
+    position->Enlarge(0, font_height);
+  }
+}
+
+}  // namespace view_text_utils
diff --git a/views/view_text_utils.h b/views/view_text_utils.h
new file mode 100644
index 0000000..5e292b9
--- /dev/null
+++ b/views/view_text_utils.h
@@ -0,0 +1,75 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// This file defines utility functions for working with text in views.
+
+#ifndef VIEWS_VIEW_TEXT_UTILS_H_
+#define VIEWS_VIEW_TEXT_UTILS_H_
+
+#include <string>
+
+#include "gfx/rect.h"
+#include "gfx/font.h"
+
+namespace gfx {
+class Canvas;
+class Size;
+}
+
+namespace views {
+class Label;
+class Link;
+}
+
+namespace view_text_utils {
+
+// Draws a string onto the canvas (wrapping if needed) while also keeping
+// track of where it ends so we can position a URL after the text. The
+// parameter |bounds| represents the boundary we have to work with, |position|
+// specifies where to draw the string (relative to the top left corner of the
+// |bounds| rectangle and |font| specifies the font to use when drawing. When
+// the function returns, the parameter |rect| contains where to draw the URL
+// (to the right of where we just drew the text) and |position| is updated to
+// reflect where to draw the next string after the URL.  |label| is a dummy
+// label with the correct width and origin for the text to be written; it's
+// used so that the x position can be correctly mirrored in RTL languages.
+// |text_direction_is_rtl| is true if an RTL language is being used.
+// NOTE: The reason why we need this function is because while Skia knows how
+// to wrap text appropriately, it doesn't tell us where it drew the last
+// character, which we need to position the URLs within the text.
+void DrawTextAndPositionUrl(gfx::Canvas* canvas,
+                            views::Label* label,
+                            const std::wstring& text,
+                            views::Link* link,
+                            gfx::Rect* rect,
+                            gfx::Size* position,
+                            bool text_direction_is_rtl,
+                            const gfx::Rect& bounds,
+                            const gfx::Font& font);
+
+// A helper function for DrawTextAndPositionUrl, which simply draws the text
+// from a certain starting point |position| and wraps within bounds.
+// |word_for_word| specifies whether to draw the text word for word or whether
+// to treat the text as one blurb (similar to the way URL's are treated inside
+// RTL text. For details on the other parameters, see DrawTextAndPositionUrl.
+void DrawTextStartingFrom(gfx::Canvas* canvas,
+                          views::Label* label,
+                          const std::wstring& text,
+                          gfx::Size* position,
+                          const gfx::Rect& bounds,
+                          const gfx::Font& font,
+                          bool text_direction_is_rtl,
+                          bool word_for_word);
+
+// A simply utility function that calculates whether a word of width
+// |word_width| fits at position |position| within the |bounds| rectangle. If
+// not, |position| is updated to wrap to the beginning of the next line.
+void WrapIfWordDoesntFit(int word_width,
+                         int font_height,
+                         gfx::Size* position,
+                         const gfx::Rect& bounds);
+
+}  // namespace view_text_utils
+
+#endif  // CHROME_BROWSER_VIEWS_VIEW_TEXT_UTILS_H_
diff --git a/views/views.gyp b/views/views.gyp
index bde275f..6743959 100644
--- a/views/views.gyp
+++ b/views/views.gyp
@@ -250,6 +250,8 @@
         'view.h',
         'view_constants.cc',
         'view_constants.h',
+        'view_text_utils.cc',
+        'view_text_utils.h',
         'view_gtk.cc',
         'view_win.cc',
         'widget/aero_tooltip_manager.cc',